Make GIF attachments animate in the Compose screen

Tusker/Screens/Compose/ComposeAttachmentImage.swift

@@ -13,6 +13,7 @@ struct ComposeAttachmentImage: View {
     let attachment: CompositionAttachment
     let fullSize: Bool
     
+    @State private var gifData: Data? = nil
     @State private var image: UIImage? = nil
     @State private var imageContentMode: ContentMode = .fill
     @State private var imageBackgroundColor: Color = .black
@@ -20,7 +21,9 @@ struct ComposeAttachmentImage: View {
     @Environment(\.colorScheme) private var colorScheme: ColorScheme
     
     var body: some View {
-        if let image = image {
+        if let gifData {
+            GIFViewWrapper(gifData: gifData)
+        } else if let image {
             Image(uiImage: image)
                 .resizable()
                 .aspectRatio(contentMode: imageContentMode)
@@ -54,9 +57,23 @@ struct ComposeAttachmentImage: View {
                 // currently only used as thumbnail in ComposeAttachmentRow
                 size = CGSize(width: 80, height: 80)
             }
-            PHImageManager.default().requestImage(for: asset, targetSize: size, contentMode: .aspectFill, options: nil) { (image, _) in
-                DispatchQueue.main.async {
-                    self.image = image
+            let isGIF = PHAssetResource.assetResources(for: asset).contains(where: { $0.uniformTypeIdentifier == UTType.gif.identifier })
+            if isGIF {
+                PHImageManager.default().requestImageDataAndOrientation(for: asset, options: nil) { data, typeIdentifier, orientation, info in
+                    if typeIdentifier == UTType.gif.identifier {
+                        self.gifData = data
+                    } else if let data {
+                        let image = UIImage(data: data)
+                        DispatchQueue.main.async {
+                            self.image = image
+                        }
+                    }
+                }
+            } else {
+                PHImageManager.default().requestImage(for: asset, targetSize: size, contentMode: .aspectFill, options: nil) { (image, _) in
+                    DispatchQueue.main.async {
+                        self.image = image
+                    }
                 }
             }
         case let .video(url):
@@ -70,13 +87,34 @@ struct ComposeAttachmentImage: View {
             imageContentMode = .fit
             imageBackgroundColor = .white
         case let .gif(data):
-            if let image = UIImage(data: data) {
-                self.image = image
-            }
+            self.gifData = data
         }
     }
 }
 
+private struct GIFViewWrapper: UIViewRepresentable {
+    typealias UIViewType = GIFImageView
+    
+    @State private var controller: GIFController
+    
+    init(gifData: Data) {
+        self._controller = State(wrappedValue: GIFController(gifData: gifData))
+    }
+    
+    func makeUIView(context: Context) -> GIFImageView {
+        let view = GIFImageView()
+        controller.attach(to: view)
+        controller.startAnimating()
+        view.contentMode = .scaleAspectFit
+        view.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)
+        view.setContentCompressionResistancePriority(.defaultLow, for: .vertical)
+        return view
+    }
+    
+    func updateUIView(_ uiView: GIFImageView, context: Context) {
+    }
+}
+
 struct ComposeAttachmentImage_Previews: PreviewProvider {
     static var previews: some View {
         ComposeAttachmentImage(attachment: CompositionAttachment(data: .image(UIImage())), fullSize: false)